Their market cap today is ~5.6B at $18 a share. Jumping back to December 7, they were worth $23, so ~7.3B market cap. So, close to 4% of outstanding shares.
Agreed this metric is better, but the article also notes that these two firms own 70% of SolarWinds so any meaningful sale would be large by this measure I think?
1) Is $286m a lot?
2) How many insiders are there and what is normal behavior for them?
3) Are these well-timed sales abnormal or are we only looking because of the headlines?
A quick read of this story doesn't seem to answer these questions.